Electric valve circuit



26, 1939. e. WOLF ELECTRIC VALVE CIRCUIT Filed Jan. 31, 1938 A9 Vappr-pres Inventor": Gunter W0 f,

b flay QTA AM 9 His Attorney Patented 13cc. 26, 1939 UNITED STATES ELECTRIC VALVE CIRCUIT Giinter Wolf, Finkenkrug, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic in. b. H., Berlin, Germany, a corporation of Germany Application January 31, 1938, Serial No. 188,012 In Germany February 4, 1937 4 Claims.

My invention relates to electric valve circuits and more particularly to control or excitation circuits for electric valve means of the type employing ionizable mediums such as vapors.

Heretofore arc discharges within electric valve means of the type employing ionizable mediums, such as vapors, have been initiated in various Ways.

For example, in electric valve means of the type employing cathodes of the self-reconstructing type, such as mercury pool cathodes, arc discharges have been initiated by striking electrodes which are brought into engagement with the surface of the mercury pool cathodes and withdrawn therefrom to establish arc discharges between the electrodes and the mercury pools, thereby ionizing the mercury vapor. Another way in which are discharges have been initiated is by the employment of starting electrodes in proximity to the mercury pool cathodes but not in contact therewith, and on which there is impressed relatively high voltages, establishing discharges between the electrodes and the mercury pool cathodes eifecting thereby ionization of the mercury vapor. A still further type of control has involved the use of starting or arc initiating electrodes which employ the vapor-pressure principle; that is, the starting electrode of this type is placed in contact with the mercury pool cathode and is energized from a suitable auxiliary source to raise the temperature of the starting electrode to a value sufiicient to cause ebullition of the mercury of the cathode, which in turn efiects ionization of the mercury vapor. In a still further type of control, a control electrode having an extremity thereof immersed below the surface of the mercury pool cathode is energized to initiate an arc discharge between the principal electrodes of the electric valve. This latter type of contol member is sometimes referred to as a make-alive, a resistance electrode, or an immersion-ignitor control member. Control members of this type are constructed of materials having a specific electrical resistivity substantally greater than the resistivity of the associated cathode, and the arc discharge is established by transmitting a current of sufficient magnitude through the immersion-ignitor control member to establish a potential gradient of sufiicient value to effect ionization of the mercury vapor. One material of which control members of this type may be constructed is the material disclosed and claimed in United States Letters Patent No. 1,822,742, granted September 8, 1931 on an application of Karl B. McEachron.

It has been found that an output characteristic of an electric valve means of the type employing an ionizable medium may be controlled conveniently by controlling the time of the energization of the control member during the positive half cycles of applied anode-cathode voltage.

Of course, some of the above mentioned types of control members are unsuited to this method of control. For example, in the case of control members of the vapor-pressure type in which the are discharges are maintained only so long as the anode is positive relative to the cathode. Of course, the actual period of conduction for each initiation of an arc discharge depends upon the constants of the associated supply circuit and the power factor of the load supplied by the electric valve means. Since the arc discharge may be initiated at any particular time during the positive half cycles of applied anode-cathode voltage when make-alive or immersion-ignitor type control members are employed, the average output voltage or current of an electric valve means may be controlled by controlling the phase of the times of the energization of the control members during the positive half cycles of applied anode-cathode voltage,

It will be understood from a consideration of the above that each type of control of electric valve means of this type offers inherent advantages and disadvantages. In accordance with my invention described hereinafter, I provide improved electric valve circuits whereby there are afforded advantages in operating characteristics and advantages in apparatus economy and apparatus life greater than those offered by the arrangements of the prior art.

It is an object of my invention to provide a new and improved electric valve means and associated control circuits.

It is another object of my invention to provide a new and improved control or excitation circuit for electric valve means of the type employing make-alive or immersion i gnitor control members.

It is a further object of my invention to provide a new and improved electric valve circuit in which electric valve means employing a pair of different types of control members are used to increase the apparatus economy and apparatus life.

In accordance with the illustrated embodiment of my invention, I provide an electric valve translating circuit comprising an electric valve means of the type employing an ionizable medium, such as mercury vapor, and which includes a pair of anodes, a single cathode and a pair of control members which are of different types. One of the control members is of the make-alive or immersion-ignitor type which is to be employed when it is desired to control an output characteristic of an associated load circuit; the other control member is of the vaporpressure type intended to be used when the arc discharges may be initiated at the beginning of the positive half cycles of applied anode-cathode voltages. The immersion-ignitor control member is energized at a frequency double that of the associated supply circuit and the vapor-pressure ignitor is energized from an auxiliary source to raise the temperature thereof to that value sufficient to assure an incipient discharge between the anodes and the cathode when the respective anode voltages become positive. A suitable switching means is also provided to permit selective energization of the respective control members or ignitors in accordance with the specific requirements of the load or application.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims. The figure diagrammatically illustrates an embodiment of my invention in which an electric valve means employing a pair of diiferent types of control members is used.

Referring now to the figure of the accompanying drawing, my invention is diagrammatically illustrated as applied to an electric valve translating circuit for transmitting power between an alternating current circuit l and a direct current circuit 2 through electric translating apparatus comprising a transformer 3 and an electric valve means 4. The electric valve means 4 comprises an envelope 5, a pair of anodes 9 and l, a cathode 8 of the self-reconstructing type such as a mercury pool cathode, and a control member 9 of the immersion-ignitor type having an extremity thereof immersed below the surface of the mercury pool cathode. The control member 9 is constructed of a material having a specific electrical resistivity greater than the resistivity of the mercury pool cathode and may be constructed of a suitable material, such as silicon, boron-carbide, or the material disclosed and claimed in the above-mentioned patent granted on an application of Karl B. McEachron.

In order to energize the control member 9 to initiate arc discharges between the anodes 6 and l and the cathode 8 during the respective positive half cycles of the voltages applied to the anodes 9 and l, I provide an excitation circuit H] which energizes control member 9 at a frequency double that of the alternating current supply circuit l, or, in other words, at a frequency double that of the voltage applied to the anodes 6 and 'i. As illustrative of the Way in which the circuit l9 may be arranged to supply double frequency current to the control member 8, I have shown an electric valve circuit ll including a transformer i 2 and a pair of unidirectional conducting devices, such as electric valves l3, which transmit an unfiltered unidirectional pulsating current of double frequency to the immersion-ignitor control member 9. It is to be understood that any other suitable arrangement well known in the art may be employed to effect energization of the control member 9 at the desired frequency.

I provide a control member Id of the vaporpressure type arranged to be heated to effect ebullition of the mercury of cathode 8 to ionize the mercury vapor. Control member I4 may be constructed of any suitable material whose action in initiating an arc discharge is a function of temperature, such as uranium or other suitable material.

To permit selective energization of control members 9 and I4, I provide a suitable circuit controlling means such as a switch l5 having a movable contact member l6 and stationary contact members I! and IS. When switch I5 is in the left-hand position, control member 9 is connected to be energized from excitation circuit In; and when switch [5 is in the right-hand position, control member Hi is energized from any suitable source such as a battery [9. If desired, a source of alternating current may be employed to energize control member H.

To shift the phase of the electrical impulses impressed on control member 9 by excitation circuit I0, I employ a suitable phase shifting arrangement such as a rotary phase shifter 29 which may be connected to the alternating current circuit I through switch 2 I.

If it is desired to operate the system so that the electric valve means i is fully conductive and so that the average voltage impressed on the direct current load circuit 2 is maximum, the movable contact member it of switch l5 may be moved to the right-hand position to energize the control member M from the source !9. If it is desired to control the voltage and hence the current in the load circuit 2, the movable contact member 16 of switch i5 may be moved to the left-hand position so that the control member 9 is energized from the excitation circuit l0. Due to the fact that the control member 9 is energized at a frequency double that of the alternating current circuit I, the control member 9 initiates arc discharges twice during each cycle of voltage so that current is conducted alternately by anodes 6 and 7. In this manner, where the electric valve means 4 is to operate under fully conductive conditions, the control member 9 may be relieved of duty by employing control member Hi, thereby extending the useful life of the electric valve means.

While I have shown and described my invention as applied to a particular system of connections and as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination, an alternating currentcircuit, a load circuit, electric translating apparatus connected therebetween and including an electrical network and an electric valve means of the type employing a mercury vapor as an ionizable medium and having a pair of anodes, a mercury pool cathode, a control member of the vaporpressure type associated with said cathode and a control member of the immersion-ignitor type associated with said cathode, the latter control member being constructed of a material having a specific electrical resistivity relatively large compared with that of the associated cathode, and means for selectively energizing the control members.

2. In combination, an alternating current circuit, a load circuit, electric translating apparatus connected therebetween and including an electrical network and an electric valve means of the type employing a mercury vapor or an ionizable medium and having a pair of anodes, a mercury pool cathode, a control member of the vaporpressure type associated with said cathode and a control member of the immersion-ignitor type associated with said cathode and being constructed of a material having a specific electrical resistivity relatively large compared with that oi the associated cathode, and means for selectively energizing the control members to render said electric valve means conductive at the beginning of each positive half cycle of the applied anode potentials or to render said electric valve means conductive at predetermined other points during each positive half cycle of the anode-cathode potentials.

3. In combination, an alternating current circuit, a load circuit, electric translating apparatus connected therebetween and including an electrical network and an electric valve means of the type employing an ionizable medium and having an anode, a self-reconstructing cathode, a control member arranged to maintain the ionizable medium in an ionized state and a control member of the immersion-ignitor type, the latter being constructed of a material having a specific electrical resistivity relatively large compared with that of the associated cathode, and means for selectively energizing the control members.

4. In combination,,an alternating current circuit, a load circuit, electric translating apparatus connected therebetween and including an electrical network and an electric valve means of the type employing an ionizable medium and having a pair of anodes, a self-reconstructing cathode, a control member arranged to maintain the ionizable medium in an ionized state and a control member of the immersion-ignitor type, the latter being constructed of a material having a specific electrical resistivity relatively large compared with that of the associated cathode, means for continuously energizing the first mentioned control member, frequency changing means connected between said alternating current circuit and the immersion-ignitor control member for energizing the immersion-ignitor control member to effect ionization of said medium at predetermined times during the respective positive half cycles of anode-cathode voltages, and means for selectively energizing the control members.

GiiNTER 'WOLF. 

